TENTECH MPK254 User manual

Formato: 137mm x 190mm
P. 17
P. 03
Manual de uso
Micro-ohmímetro digital
Digital micro-ohmmeter User guide
www.tentech.com

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MPK-254
Digital micro-ohmmeter
User’s guide
GF-2045
© 2016 TENTECH. All rights reserved.

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
Safety Precautions
•This equipment should be operated only by qualified and duly trained people,
closely observing the corresponding safety regulations and instructions
contained in the present User guide.
•It should be checked that the item to be measured is voltage free.
•Before starting with the measurements, be sure that the battery is well charged
and that the line voltage is between specified limits.
•Do not connect or disconnect the test leads during the measurement.
•There are no adjustable parts or parts that can be replaced by the user within the
equipment. Taking out the Control Panel in order to have an access to the
internal parts may be dangerous as there are high voltages inside, capable of
causing fatal accidents.
•Cleaning of this instrument should be carried out using a soft cleaning liquid,
after verifying that it doesn't attack the plastic parts used in the case and in the
Control Panel of this equipment.
This equipment should be used only by a trained and competent
person, strictly applying suitable safety rules.
Used symbols
Caution, refer to User Guide.
Equipment complies with current EU Directives.
The rubbish bin with a line through it means that in the European Union,
the product must undergo selective disposal for the recycling of electric
and electronic material, in compliance with Directive WEEE 2002/96/EC.

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Index
1. Description......................................................................................................... 6
1.1. Operating principle...................................................................................... 6
2. Control panel ..................................................................................................... 7
3. Power supply ..................................................................................................... 8
3.1. Battery condition ......................................................................................... 8
3.2. Battery charger ........................................................................................... 8
4. Measurement..................................................................................................... 9
5. Messages ........................................................................................................ 10
6. Some notes about accuracy............................................................................. 12
7. RS232 output................................................................................................... 13
8. Cleaning .......................................................................................................... 13
9. Replacement fuse............................................................................................ 13
10. Technical specifications ................................................................................. 14
11. Warranty........................................................................................................ 16

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1. Description
The MPK-254 micro-ohmmeter is a portable, microprocessor controlled
instrument, used to accurately measure very low contact resistances of
breakers and switches, busbars, transformers and engines windings, etc,
with test currents from 1 mA to 5 A.
•Kelvin architecture (four-terminal method).
•Digital reading, alphanumeric display.
•Up to 4½ digits readings.
•Powered by rechargeable battery.
•1 µresolution.
•200 maximum reading.
1.1. Operating principle
This device uses the Kelvin Bridge architecture, with four terminals,
avoiding testing leads resistance to cause error during measurement. The
operator may choose test current and the reading is obtained by
comparison through internal high-stability standards. The result appears
in the alphanumeric display that is very easy to read.

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2. Control panel
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Fuse.
Power cord connector.
On/Off switch.
Battery charge indicator.
Current terminal (C+).
Potential terminal (P+).
Potential terminal (P-).
Current terminal (C-).
RS232 data output.
Alphanumeric display. Shows both
the measured resistance value and
messages to the operator.
Start key.
Stop key.
Hold key. It retains the last
measurement in the display.
Battery key. To measure the battery
charge condition.
Test current control.
Range and test current selector.
On led.

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3. Power supply
Internal battery powered, rechargeable, 12 V - 7 Ah.
At the end of the useful life, the battery has to be recy
cled or disposed of
properly in order to take care of the environment.
3.1. Battery condition
The charge condition of the battery can be verified before or during the
resistance measurement. In order to achieve that, the operator has to
press the battery key while the equipment is turned on. The bargraph
shows remaining charge as a percentile value. If during measurement the
charge of the battery achieves a critical level, the display will show the
BAT message notifying that the charge level is low. After a few minutes
the measurement will be automatically interrupted in order to preserve the
battery from a deep discharge that is prejudicial for its expected useful
life.
3.2. Battery charger
The built-in battery charger is always active when the equipment is
connected to the mains supply, even if the On/Off switch is turned off.
Charging procedure:
•Check that the On/Off switch is in Off.
•Connect the equipment to the mains supply.
•The battery charge indicator will keep on lightning with a red light
up to completing the charge. At that point, it will change to a green light,
being like this up to the equipment disconnection from the mains supply.
If the ON/OFFswitch was pressed, the display will indicate
CHARGING BAT.

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4. Measurement
It should be checked that the item to be measured is voltage free.
1. Before turning the equipment On, connect the test leads to the item to
be measured and to the front panel terminals.
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R
The alligator clamps in the drawing are only for illustration.
2. Using the test current selector , choose the range and the current
to be used.
3. Switch the equipment On using the On/Off .
4. The PRESS START message will appear showing that measurement
can be started. Press the Start key. Depending on the position of
the test current control the LOW CURRENT message will turn
up.
5. Turning the test current control clockwise increases the current.
Adjust this control until obtaining the desired value or until the current
indicator (bargraph) indicates 100%. The bargraph will show the test
current value as a percentage of the nominal value selected by using
the test current selector .

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6. The lowest current for measuring is 10% of the nominal value. It is
important to consider that the measurement errors increase while test
current decreases. The equipment accuracy is specified for test
currents higher than 80%.
7. The display will show the resistance value measured and the
corresponding unit ([ohms], m[milli-ohms] or µ[micro-ohms]).
8. The value can be retained in the display by pressing the hold key.
Pressing this key again, the value will be released.
9. Press the Stop key in order to finish the measurement. Do not turn
Off the equipment without pressing the Stop key before.
10. Finally, when finishing measurements, turn the equipment Off using
the On/Off switch.
Precaution:
Do not connect or disconnect the test leads during the
measurement.
5. Messages
TENTECH MPK-254
When turning the equipment On using the On/Off switch, this
introductory message appears for a while.
WAIT...
This message appears each time the equipment needs to adjust any
parameter in order to optimize the readings.
PRESS START
The equipment is ready to start a measurement, thus the operator has to
press the Start key.

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LOW CURRENT
It shows that the test current is not enough to carry out the reading. It
appears at the beginning of each test and it keeps on being there up to
the operator rotates the test current control clockwise, as necessary
for the test current to be higher than 10 % of the nominal current in the
range. The inappropriate connection of the cables may cause a difficult
circulation of test current. If this message keeps on being displayed,
please check that the current cables are connected appropriately.
OVERRANGE
It indicates that the measured resistance is higher than the maximum
value readable in the selected range.
H
Indicates that the value is the one retained in the display when pressing
the hold key.
BAT
It shows that the battery is quite discharged. It is necessary the battery to
be recharged.
CHARGING BAT
It appears when the equipment is connected to mains supply and the
ON/OFswitch, is ON.

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6. Some notes about accuracy
In order to obtain the specified accuracy, the operator has to adjust the
test current to a value higher than the 80% of the nominal value. If it were
necessary, it is possible to use a lower current, but by doing this the
accuracy will be affected.
MPK-254 has an auto-compensation system that automatically eliminates
the error produced by internal offset. Thus, it is not necessary to carry out
measurements by reversing the polarity in order to compute the average
value. Nevertheless, if the operator suspect that there is a difference of
temperature between the contact points that would can generate
thermoelectric voltages, it is necessary to carry out two measurements by
reversing the current cables and so, the circulation sense of the current
through the resistance under measurement. The resistance value to be
measured will be the average between the values in one sense and in the
contrary (direct and inverse current).

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7. RS232 output
The equipment has an RS232 data output in the control panel that can
be used to register measurements in a serial printer or data collector. The
outputs are the following ones:
Pin 2: Rx ; Pin 3: Tx ; Pin 5: Gnd;
Rate: 4800 bps
8 bits - no parity - 1 stop bit (8,n,1)
Note: In order to assure the compatibility with most printers available in
the market, the resistance units are shown with the following symbols:
uR = micro-ohm
mR = milli-ohm
R = ohm
8. Cleaning
The panel, terminals and connectors of the equipment must stay dry and
clean. Cleaning should be made using a wet cloth in water and a soft
detergent or isopropyl alcohol (be sure that the products to be used for
cleaning does not affect plastic).
9. Replacement fuse
To check the instrument fuse , remove it with a screw driver. If the fuse
is ruptured replace it by another with the following specifications:
Fuse Schurter, model SPT 5x20 (Time-lag) 5A/250V. High breaking capacity.

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10. Technical specifications
Test currents :
1 mA - 10 mA - 100 mA - 1 A - 5 A.
Each current may be continuously adjustable from
0 to 100%.
Resistance ranges :
0 - 20 m@ 5 A.
0 - 600 m@ 5 A.
0 - 200 m@ 1 A.
0 - 2000 m@ 100 mA.
0 - 20 @ 10 mA.
0 - 200 @ 1 mA.
Resolution :
1 µ@ 5 A.
Output voltage :
Up to 10 Vd.c. @ 1 A (open circuit).
Measurement principle :
Four-terminal, Kelvin-type.
Basic accuracy :
± 0.2% of reading ± 2 digits.
Advanced features :
Digital direct reading of very low resistances in the
alphanumerical display, with up to 4½ digits. Very
fast and accurate measurements.
Serial data output :
RS232 @ 4800 bps. Suitable for data collection in
an external serial printer, computer or data-logger.
Environmental protection :
IP54 (with closed lid).
Safety class :
Meets the requirements of IEC 61010-1.
Power supply :
Rechargeable battery 12 V - 7 Ah.
Built-in battery charger :
220-240 V~ mains supply.
Operating temperature
range :
-5°C to 50°C.
Storage temperature range :
-25°C to 65°C.
Humidity range :
95% RH (non condensing).
Weight :
Approx. 8
.7 kg (including accessories).

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Dimensions :
378 x 308 x 175 mm.
Accessories :
2 Combined current and potential leads (1.8 m).
1 Communication cable (RS232).
1 Power cord.
1 User guide.
1 Carrying bag.
Subject to technical change without notice.

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11. Warranty
TENTECH warrants the products for one year from date of shipment.
We will repair, without charge, any defects due to faulty materials or
workmanship. For warranty repair information, contact us or visit our
webpage www.tentech.com. This warranty does not apply to
accessories or damage caused where repairs have been made or
attempted by others. For the accessories and batteries the period of
warranty is six months.
TENTECH’ warranty obligation is limited, at TENTECH’ option, to free of
charge repair or replacement of the defective product within the warranty
period, or to refund of the purchase price.
Any costs for transportation to manufactures facility is the responsibility of the
customer. The manufacturer assumes no risk for damage in transit.
If TENTECH determines that the failure was caused by misuse, alteration,
accident or abnormal condition or handling, you will be charged for the
repair and transportation.
The manufacturer does not take any responsibility for any eventual
damage due to the use or impossibility to the use of the equipment
such as the loss of memory data, accidents in the field, loss of
profit, etc.

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MPK-254
Micro-ohmímetro digital
Manual de uso
© 2016 TENTECH. Todos los derechos reservados.

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
Precauciones de Seguridad
•Estos equipos deben ser operados únicamente por personas calificadas,
debidamente entrenadas, respetando rigurosamente las normas de seguridad
pertinentes y las indicaciones contenidas en el actual manual de uso.
•Se debe verificar que el elemento a medir no esté energizado.
•Antes de comenzar las mediciones se debe verificar que la batería esté con
carga y que la tensión de línea está entre los límites especificados.
•No conecte o desconecte las puntas de prueba durante una medición.
•No existen partes ajustables o reemplazables por el usuario en el interior del
equipo. Retirar la tapa para acceder a su interior es peligroso, porque existen
tensiones elevadas, capaces de provocar accidentes fatales.
•La limpieza de este instrumento se debe realizar empleando un líquido limpiador
suave, verificando previamente que no ataca los materiales plásticos utilizados.
Este equipo debe ser operado únicamente por personas calificadas,
aplicando rigurosamente las normas de seguridad pertinentes.
Símbolos utilizados en el equipo
Atención, referirse al manual de uso.
El equipo está conforme con las directrices actuales de la U.E.
El contenedor de basura tachado significa que, en la Unión Europea, el
producto deberá ser objeto de una recogida selectiva de los residuos
para el reciclado de los aparatos eléctricos y electrónicos de
conformidad con la directiva WEEE 2002/96/CE.

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Índice
1. Descripción...................................................................................................... 20
1.1. Principio de funcionamiento ...................................................................... 20
2. Función de los controles del panel................................................................... 21
3. Alimentación.................................................................................................... 22
3.1. Estado de carga de la batería ................................................................... 22
3.2. Cargador de batería.................................................................................. 22
4. Operando el equipo ......................................................................................... 23
5. Mensajes del display........................................................................................ 25
6. Consideraciones acerca de la exactitud........................................................... 26
7. Salida RS232................................................................................................... 26
8. Limpieza .......................................................................................................... 27
9. Cambio de fusible............................................................................................ 27
10. Especificaciones técnicas .............................................................................. 28
11. Término de Garantía...................................................................................... 30

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1. Descripción
El micro-ohmímetro digital MPK-254 es un instrumento portátil,
controlado por microprocesador, destinado a medir con alta precisión
resistencias muy bajas de contacto de disyuntores, llaves, barras
conductoras, bobinados de transformadores y motores, etc., con
corrientes de prueba desde 1 mA hasta 5 A. Entre sus principales
características se destacan las siguientes:
•Controlado por microprocesador.
•Utiliza el método de los 4 terminales.
•Lectura digital, en display alfanumérico.
•Indicación de hasta 4½ dígitos.
•Batería recargable.
•Resolución de 1 µ.
•Lectura máxima de 200 .
•Salida de datos RS232.
1.1. Principio de funcionamiento
Utiliza la arquitectura del Puente de Kelvin, de cuatro terminales, evitando
que la resistencia propia de los cables de prueba introduzcan errores en
las mediciones. La corriente de prueba es seleccionable por el operador y
la indicación se obtiene por comparación con patrones internos de alta
estabilidad. El resultado es presentado en un visor alfanumérico de fácil
lectura.

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2. Función de los controles del panel
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Fusible.
Entrada de tensión de red.
On/Off - Llave de encendido.
Led indicador de carga de batería.
Borne positivo de corriente (C+).
Borne positivo de potencial (P+).
Borne negativo de potencial (P-).
Borne negativo de corriente (C-).
Salida RS232
Display alfanumérico, indicada el
valor de resistencia bajo ensayo y
avisos al usuario.
Start - Tecla de inicio del ensayo.
Stop - Tecla para finalizar el ensayo.
Hold - Mantiene congelada en el
display la última medición.
Battery -
Tecla pulsadora para medir
el estado de la batería.
Test current - Control de ajuste de
corriente.
Selector de rangos y de
corrientes.
On -Led de encendido.